2-amino-2-(1,4-cyclohexadienyl) acetic acid

ABSTRACT

2-Amino-2-(1,4-cyclohexadienyl)acetic acid is a new intermediate which joins to 6-aminopenicillanic acid or 7-aminocephalosporanic acid to yield, respectively, Alpha -amino-(1,4cyclohexadienyl)methyl-penicillin or 7-(2-amino-2-(1,4cyclohexadienyl)acetamido)-cepnalosporanic acid which are antibacterial agents.

United States Patent 15] 3,682,981 Weisenborn et al. [451 Aug. 8, 1972[54] 2-AMINO-2-(1,4-CYCLOHEXADIENYL) [56] References Cited ACETIC ACIDOTHER PUBLICATIONS [72] Inventors: Frank Lee Weisenbom, Somerset;

J se h Edward 9 mm, Nort'h Shoulders et al., J .A.C.S. 90, 2992 (1968)swick; Georges Gu t v B h, Snow et al., J. Org. Chem. 33, 1774, (1968)Hightstown; Jack Bernstein, New Jandacek, PhD. Thesis, 1968, abstractonly Brunswick, all of NJ. Dane et al., Angew Chem. Inter. Ed. 1, p. 658(1962) [73] Asslgnee: Squlbb & Sons New Primary Examiner-Lorraine A.Weinberger York, NY. Assistant Examiner-Robert Gerstl Filed: July 1969Attorney-Lawrence S. Levinson, Merle J. Smith and 211 App]. No.: 839,633Donald Penella Related U.S. Application Data [5 7] ABSTRACT 2] DivisionOf Set N0. u y 1968, Pat. 2-Amino-2-(1,4-cyclohexadienyl)acetic acid isa new ,819. intermediate which joins to 6-aminopenicillanic acid or7-aminocephalosporanic acid to yield, respectively, U.S- Cl- N, A, aamino l 4 cyclohexadienyl)methybpenicillin or 7- 260501-11 260/518260/544 260/546 [2-amino-2-( l,4-cyclohexadienyl)acetamido]-cep- [51]Int. Cl ..C07c 101/28 nalosporanic acid which are antibacterial agents[58] Field of Search ..260/468, 514, 396 N 3 Claims, N0 Drawings2-AMINO-2-(l ,4-CYCLOHEXADIENYL) ACETIC ACID This application is adivision of application Ser. No. 741,852, filed July 2, 1968 now US.Pat. No. 3,485,819.

SUMMARY OF THE INVENTION This invention relates toa-amino-cyclohexadienylalkylene-penicillins and cephalosporins of theformula A represents the 6-aminopenicillanic acid (6-APA) moiety, i.e.,

wherein R is hydrogen, lower alkyl or a salt forming ion, e.g., analkali metal as sodium or potassium, an alkaline earth metal likecalcium or magnesium, or that of an organic base like dibenzylamine,N,N- dibenzylethylenediamine or the like.

A also represents the 7-aminocephalosporanic (7- ACA) acid moiety, i.e.,

(III) S -HNCH-C/H kHz -N CHzX wherein R has the same meaning as aboveand X is hydrogen, lower alkanoyloxy, e.g., acetoxy,

propanoloxy or the like, the radical of a nitrogen base such asmethylamino, dimethylamino or the.like, or a quaternary ammonium radicallike l-pyridinium. In addition X and R may represent a bond linkingcarbon and oxygen in a lactone ring.

R represents hydrogen, lower alkyl or lower alkoxy,

R R, R, R and R each represents hydrogen or lower alkyl.

m represents 1 or 2.

n represents 0, l, 2, 3 or 4.

The lower alkyl and lower alkoxy groups in'the above formulas includestraight and'branched chain radicals such as methyl, ethyl, propyl,isopropyl, butyl, isobutyl, t-butyl, amyl, methoxy, ethoxy, propoxy,isopropoxy and the like.

Except where otherwise indicated, the symbols in the foregoing formulasand those which follow all have the meaning defined above.

The new compounds of formula I may be prepared by coupling an activatedform of a cyclohexadienyl-aaminoalkanoic acid, having the formula withthe 6-APA moiety of formula II or 7-ACA moiety of formula III.

If one or both of R and R is hydrogen, the amino group is best protectedbefore coupling for an efficient 5 process. Protecting groups which maybe used to protect the amino group during the reaction of the acidcompound with the 6-APA or 7-ACA compound include, for example,triphenylmethyl, t-butoxycarbonyl,B,B,B-trichloroethoxycarbonyl.4-oxo-2-pentenyl-2,lcarbomethoxy-l-propenyl-Z or the like. These are formed by reacting theacid of formula IV, wherein one or both of R and R are hydrogen, with acompound such as triphenylmethylchloride, t-butyl azidoformate,B,B,B-trichloroethyl chloroformate. acethylacetone. methylacetoacetateor the like. After the coupling reaction, the protecting group isremoved, e.g., by treatment with aqueous acetic acid, trifluoroaceticacid, zinc-acetic acid, or aqueous mineral acid, respectively to givethe compound with the free or monosubstituted amino group.

Alternately the amino group may be protected by protonation as the saltform before and during the subsequent coupling reaction.

In those cases in which both R and R represent lower alkyl, noprotection of the amino group is necessary.

The coupling is preferably effected by conversion of the acid to anactivated form such as the acid chloride, azide, p-nitrophenyl ester ormixed anhydride, or by condensing in the presence of a carbodiimide suchas dicyclohexylcarbodiimide.

The starting materials of formula IV may be prepared by reducing acompound of the formula (R n R4 or a metal salt thereof, e.g., alkalimetal salt, alkaline earth metal salt or the like, with sodium orlithium in liquid ammonia followed by treatment with an alcohol such asethanol, t-butanol, followed by treatment with ammonium chloride, orother amine hydrochloride.

The products of this invention form salts which are also part of theinvention. Basic salts form with the acid moiety as discussed above inconnection with the symbol R. Acid addition salts also form with thea-amino nitrogen. Such acid salts include, for example, inorganic saltssuch as hydrohalides, e.g., hydrobromide, hydrochloride, hydroiodide,sulfate, nitrate, phosphate, borate, etc., and organic salts such asacetate, oxalate, tartrate, malate, citrate, succinate, benzoate,ascorbate, methanesulfonate and the like. It is frequently convenient toisolate and purify the product by forming a soluble or insoluble salt,as desired, thenregenerating the free compound, by neutralization, forexample.

Preferred compounds within the group described b formula I have theformula especially when R is hydrogen or lower alkoxy (preferablymethoxy) and R to R inclusive are all hydrogen and n is 0, l, or 2,especially n is O or 1. In the most preferred embodiment A is the6-aminopenicillanic acid moiety of formula 11 and n is 0, especiallywhen all Rs represent hydrogen.

It will be appreciated that certain of the compounds of this inventionexist in different optically active forms. The various stereoisomericforms as well as the racemic mixtures are within the scope of thisinvention.

Ordinarily the new penicillin compound derived by coupling 6-APA with aseries of D-a-aminocyclohexadienalkylene carboxylic acids are of highestpotency. The configuration of the a-carbon of the aminoalkanoic acidused in the synthesis is retained in the product.

The compounds of this invention have a broad spectrum of antibacterialactivity against both gram positive and gram negative organisms such asStaphylococcus aureus, Salmonella schottmuelleri, Pseudomonasaeruginosa, Proteus vulgaris, Escherichia coli and Streptococcuspyogenes. They may be used as antibacterial agents in a prophylacticmanner, e.g., in cleaning or disinfecting compositions, or otherwise tocombat infections due to organisms such as those named above, and ingeneral may be utilized in a manner similar to penicillin G and otherpenicillins and cephalosporins. For example, a compound of formula I ora physiologically acceptable salt thereof may be used in various animalspecies in an amount of about 0.1 to 100 mg/kg daily, orally orparenterally, in single or two to four divided doses to treat infectionsof bacterial origin. By way of illustration the PD orally in mice in asingle administration is 1.3 mg/kg against Streptococcus, 8.6 mg/kgagainst Proteus and 11.8 mg/kg against Salmonelia, respectively. Up toabout 600 mg. of a compound of formula 1 or a salt thereof may be incorporated in an oral dosage form such as tablets, capsules or elixirs orin an injectable form in a sterile aqueous vehicle prepared according toconventional pharmaceutical practice. In cleaning or disinfectingcompositions, e.g., in barns or dairy equipment, a concentration ofabout 0.01 to 1 percent by weight of such compounds admixed with,suspended or dissolved in conventional inert dry or aqueous carriers forapplication by washing or spraying may be used.

The following examples are illustrative of the invention. Alltemperatures are on the centigrade scale.

GENERAL PROCEDURE 1. l,4-cyclohexadienyl-a-aminoalkanoic acid A solutionof 72.7 mmole of a-amino aryl alkanoic acid in 900 ml distilled ammonia(which has been treated with 45 mg. lithium after distillation todestroy traces of moisture) is slowly diluted with 370 ml. dry tbutylalcohol.

Over a period of 2 hours, 1.65 g. lithium (3.27 eq.) is added in smallportions until a permanent blue color is obtained. The blue reactionmixture is then treated with 38 g. of triethylamine hydrochloride. Theammonia is allowed to evaporate at room temperature overnight and theresidual solvent is evaporated at reduced pressure. The white residue istaken up in a small amount of methanol-water and added to 4 l. of cold1:1 chloroform acetone to precipitate the crude product. After 20minutes stirring the suspension is filtered and the white filter cakedried in vacuo; the filter cake is then pulverized and submitted oncemore to the precipitation process from 1:1 chloroform-acetone.

The crystalline product is obtained in high yield and purity but isslightly contaminated with lithium chloride, about 1 percent chlorinebeing found by typical analysis. The material may be used directly.

2. Methyl acetoacetate enamine of a-amino-m-( l ,4-cyclohexadienyl)alkanoic acid sodium salt 2.00 mmoles of1,4-cyclohexadienyla-aminoalkanoic acid is dissolved by warming in asolution of 108 mg. of NaOCH (2.00 mmoles) in 4.3 ml. reagent gradeMeOH. 255 mg. (0.24 ml. 2.20 mmoles) methyl acetoacetate is added andthe mixture refluxed for 45 minutes. The MeOH is almost totally strippedoff in vacuo. 5 ml. benzene is added and distilled off to a smallresidual volume. The addition and distillation of benzene is repeated toinsure complete removal of the MeOH and water. The product crystallizesout overnight from a small residual volume of benzene; the amorphouspowder obtained from benzene is quite satisfactory for further use.

3. a-amino-w-( l,4-cyclohexadienyl)alkylpenicillin 358 mg.6-aminopenicillanic acid 1.66 mmoles) are stirred well in 2.5 ml. waterwhile 0.23 ml. triethylamine are gradually added with the pH kept under8.0. Final pH is 7.4; 0.85 ml. acetone are added and the solution keptat 10 C.

1.66 mmoles of methyl acetoacetate enamine of aamino-w-(l,4-cyclohexadienyl)alkanoic acid, sodium salt are stirred in 4.25 ml.acetone at 20 C. A microdrop OF N-methylmorpholine is added followed bythe slow addition of 198 mg. of ice cold ethyl chloroformate. Water,0.43 ml., is added at this point and a turbid solution results. Thereaction is stirred for 10 minutes at 20 C.

The turbid solution of mixed anhydride is then added to the 6-APAsolution. A complete solution is observed. The solution is stirred for30 minutes at 10 C. It is then raised to room temperature and acidifiedto pH 2.0 with diluted HCl and, with good stirring, the pH is kept atthat level for 10 minutes.

The solution is then extracted with 5 ml. xylene. The aqueous layer islayered with 5 ml. methyl isobutyl ketone and the pH adjusted to 5.0with l N NaOH and chilled overnight. The resulting crystals are filteredoff, washed with water, and air dried; alternately, the aqueous layermay be lyophilized, and the product obtained as a mixture with salt maybe used directly or purified by crystallization from aqueous alcohol.

7-[a-Amino-o)-( l ,4-cycl0hexadienyl )alkanoylamidoIcephalosporanic acid452 mg. (1.66 mmole) of 7-aminocephalosporanic acid are substituted forthe 6-aminopenicillanic acid in part 3 above.

5. 7-[a-amino-w-( l,4-cyclohexadienyl)alkanoylamido] -3-(lpyridiniummethyl)-3-cephem-4-carboxylate When a 0.1 molar solution ofthe 7-[a-amino-w-( 1,4- cyclohexadienyl)alkanoylamidokcephalosporanicacid is treated with 0.5 mole pyridinium acetate at pH7 (the pH isadjusted to 7 with a few drops of aqueous pyridine solution) for severalhours at room temperature, a rapid solvolysis occurs which can befollowed by paper chromatography; when the disappearance of the startingmaterial is complete, lyophilization provides good yields of the productas a fine, white powder.

6. 7-[oz-aminow-( 1,4-cyclohexadienyl)alkaloylamido)]-3deacelylcephalosporanic acid, lactone A 0.1 molar solution of the7-[a-arnino-w-( 1,4- cyclohexadienyl)alkanoylamido]-cepha1osporanic acidis acidified with dilute hydrochloric acid to pH 1-3 and maintained atthat point until paper chromatography shows absence of startingmaterial; lyophilization gives the product as a powder which may befurther purified by crystallization from aqueous ethanol oracetonitrile.

perature, and stirring for 1.5 hours. After the reaction mixture isstirred for 1 hour at C., it is stripped at reduced pressure. Theresidue is triturated with an equal volume of water, the final pH beingadjusted to and the crude product filtered ofi'. Recrystallization fromwater gives a pure product.

EXAMPLE 1 a. D-2-Amino-2-( 1,4-cyc1o11exadieny1)acetic acid A solutionof 11.0 g. (72.7 mmole) of D-phenylglycine in 900 ml. distilled ammonia(which has been treated with 45 mg. lithium after distillation todestroy traces of moisture) is slowly diluted with 370 m1. dry tbutylalcohol.

Over a period of 2 hours, 1.65 g. lithium (3.27 eq.) is added in smallportions until a permanent blue color is obtained. The blue reactionmixture is then treated with 38 g. of triethylamine hydrochloride. Theammonia is allowed to evaporate at room temperature overnight and theresidual solvent is evaporated at reduced pressure. The white residue istaken up in a small amount of methanol-water and added to 4 l. of cold1:1 chloroform acetone to precipitate the crude product. After minutesstirring the suspension is fi1- tered and the white filter cake dried invacuo; the filter cake is then pulverized and submitted once more to theprecipitation process from 1:1 chloroform-acetone.

The white, crystalline product, 11.8 g., m.p. 297 ((1), [a] -89.7 (2 NNaOH) is quantitatively obtained but is slightly contaminated withlithium chloride, 0.6 percent ionic chlorine being found by analysis.

Analysis (corrected for LiCl content):

The n.m.r. spectrum shows absorptions at 74.17 (vinyl), 6.21

7.30 (allylic) in the ratio of 3: 1:4. b. Methyl acetoacetic esterenamine of N-2-amino-2- l,4-cyclohexadieny1)acetic acid sodium salt 306mg. D-2-amino-2-(1,4-cyc1ohexadieny1)acetic acid (2.00 mmoles) aredissolved by warming in a solution of 108 mg. of NaOCH (2.00 mmoles) in4.3 m1. reagent grade MeOH. 255 mg. (0.24 ml. 2.20 mmoles) methylacetoacetate are added and the mixture refluxed for 45 minutes. The MeOHis almost totally stripped off in vacuo. 5 ml. benzene are added anddistilled off to a small residual volume. The addition and distillationof benzene is repeated to insure complete removal of the MeOH and water.The product crystallizes out overnight from a small residual volume ofbenzene. It is filtered off, washed with benzene, and dried in vacuo.Yield 463 mg.

c. D-a-Amino-( 1,4-cyc1ohexadienyl )methylpenicillin 358 mg. of6-aminopenici1lanic acid (1.66 mmoles) are stirred well in 2.5 ml. ofwater while 0.23 ml. triethylamine are gradually added with the pH keptunder 8.0. Final pH is 7.4; 0.85 ml. acetone are added and the solutionkept at 10 C. 469 mg. methyl acetoacetate enamine of D-2-amino- 2-(l,4-cyc1ohexadieny1)acetic acid sodium salt (1.715 mmoles) are stirredin 4.25 ml. acetone at 20 C. A microdrop of N-methylmorpholine is addedfollowed by the slow addition of 198 mg. of ice cold ethylchloroformate. Water, 0.43 ml., is added at this point and a turbidsolution results. The reaction mixture is stirred for 10 minutes at 20C.

The turbid solution of mixed anhydride is then added to the 6-APAsolution. A complete solution is observed. The solution is stirred for30 minutes at 10 C, then raised to room temperature, acidified to pH 2.0with diluted HC] and, with good stirring, the pH is kept at that levelfor 10 minutes.

The solution is then extracted with 5 m1. xylene. The aqueous layer islayered with 5 m1. methyl isobutyl ketone and the pH adjusted to 5.0with 1 N NaOH and chilled overnight. The resulting crystals are filteredoff, washed with water and air dried. Yield, 272 mg. (44 percent),decomposes at 202 C.

Analysis: Calcd. for C H N O S' /H O) C. 53.31; H, 6.15; N, 11.66;

8 C, 53.50; H, 6.32; N 11.35; 8

s, s. 9 Found: S, 8. 7

lodometric penicillin titration 97, 4 percent (titr. of anhydrous cpd.99.2 percent). N.M.R. 'r4.3 (vinyl), 7.3 (allylic), 8.41, 8,48(gem-dimethyl). Ratio: 324:6.

EXAMPLE 2 493 mg. of methyl acetoacetate enamine of D-2-.

amino-3-(1,4-cyclohexadieny1)propionic acid sodium salt (1.715 mmole)are substituted for the methyl acetoacetate enamine ofD-2-amino-2-(1,4-cyclohexadienyl) acetic acid sodium salt in theprocedure of Example 1c.

The mixed anhydride is added to the 6-APA, stirred for 30 minutes at C.,brought to room temperature, acidified to pH 2.0 as in Example 1c. Thesolution is then extracted with 5 ml. of xylene. The aqueous layer islayered with 5 ml. of methyl isobutyl ketone and the pH is adjusted to5.0 with l N NaOI-l. The aqueous layer is then lyophilized to give theproduct directly, containing some sodium chloride.

EXAMPLE 3 a. D-2-amino-3-(4-methoxy-1,4-cyclohexadienyl )propionic acidBy substituting 14.2 g. (72.7 mmole) of D-0-methyltyrosine for thephenyl glycine in the procedure of Example la, D-2-amino-3-(4-methoxyl,4-cyclohexadienyl)propionic acid is obtained as a white crystallineproduct, m.p. 227 C., [01],, 50.2.

Analysis Calcd.: C, 60.89; H, 7.67; N, 7.10 Found: C, 60.8l; H, 7.45; N,7.l3

EXAMPLE 4 7-[D-2-amino-2-( l,4-cyclohexadienyl)acetamido]cephalosporanic acid By substituting 452 mg. (1.66 mmole) of 7-aminocephalo-sporanic acid for the 6-APA in part (c) and otherwisefollowing the procedure of Example 1, 7- [D-2-amino-2-(1,4-cyclohexadienyl) acetamido]cephalosporanic acid is obtained.

EXAMPLE 5 7-[D-2-amino-2-( l,4-cyclohexadienyl)acetamido1-3-deacetoxycephalosporanic acid By substituting 356 mg. (1.66 mmole) of3-deacetoxy-7-aminocephalosporanic acid for the 6-APA in part (c) andotherwise following the procedure of Example I, the above product isobtained.

EXAMPLE 6 7-[D-2-amino-3-( l,4-cyclohexadienyl)propionamido]cephalosporanic acid By utilizing the procedure of Example 2, butsubstituting 452 mg. of 7-aminocephalosporanic acid instead of 6-APA,the above product is obtained.

EXAMPLE 7 7-[D-2-amino-3-( l,4-cyclohexadienyl)-propionamido]3deacetoxycephalosporanic acid By utilizing the procedure of Example 2,but substituting 356 mg. of 3-deacetoxy-7- aminocephalosporanic acid forthe 6-APA, the above product is obtained.

EXAMPLE 8 7-[D-2-amino-3-(4-methoxy-1,4-cyclohexadienyl)propionamido]cephalosporanic acid By utilizing 544 mg. of methylacetoacetate ester enarnine ofD-2-amino-3-(4-methoxy-1,4-cyclohexadienyl)propionic acid sodium salt ofExample 3 and 7- aminocephalosporanic acid as in Example 4, the aboveproduct is obtained.

EXAMPLE 9 7-[ D-2-amino-3-(4-methoxyl ,4-cyclohexadienyl)propionamido]3deacetoxycephalosporanic acid By utilizing 544 mg. ofmethyl acetoacetate enamine of D-2-amino-3-( 4-methoxy-l,4-cyclohexadienyl)propionic acid sodium salt of Example 3 and 3-deacetoxy-7-aminocephalosporanic acid, as in Example 4, the aboveproduct is obtained.

EXAMPLE l0 7-[2-amino-2-( l,4-cyclohexadienyl)acetamido]-3-(pyridiniummethyl)-3-cephem-4-carboxylate This compound is obtained asthe acetate by utilizing part 5 of the general procedure employing7-[2-amino- 2-( 1,4-cyclohexadienyl )acetamido]cephalosporanic acid.

EXAMPLE 1 1 7-[ 2-amino-3-( l,4-cyclohexadienyl)propionamido]3-1pyridiniummethyl)-3-cephem-4-carboxylate This compound is obtained asthe acetate by utilizing part 5 of the general procedure employing7-[2-amino- 3-( l ,4-cyclohexadienyl )propionamido] cephalosporanicacid.

EXAMPLE l2 7-[2-amino-3-(4-methoxyl ,4-cyclohexadienyl)propionamido]-3-( l-pyridiniummethyl )-3- cephem-4-carboxylate Thiscompound is obtained as the acetate by utilizing part 5 of the generalprocedure employing 7-[2-amino- 3-( 4-methoxyl ,4-cyclohexadienyl)propionamido] cephalosporanic acid.

EXAMPLE l3 7-[2-amino-2-( l,4-cyclohexadienyl)acetamido1-3-deacetylcephalosporanic acid lactone The use of7-[2-amino-2-(1,4-cyclohexadienyl)acetamido1-cephalosporanic acid as thesubstrate in part 6 of the general procedure gives the lactone as thehydrochloride.

EXAMPLE l4 7-[2-amino-3-( l ,4-cyclohexadienyl )propionamido]-3-deacetylcephalosporanic acid lactone The use of 7-[2-amino-3-(l,4-cyclohexadienyl)propionamido]cephalosporanic acid as the substratein part 6 of the general procedure gives the lactone as thehydrochloride.

EXAMPLE DL-a-amino-(4-methoxy-l ,4-cyclohexadienyl )methylpenicillin Bysubstituting DL-4-methoxyphenyl glycine for the phenyl glycine in part aand otherwise following the procedure of Example 1, the above product isobtained.

EXAMPLE l6 7[DL-2-amino-2-(4-methoxy-1,4-cyclohexadienyl)acetamido1-cephalosporanic acid By making thesubstitution of .DL-4-methoxyphenyl glycine as in Example 15 and furthersubstituting 7- aminocephalosporanic for the o-aminopenicillanic acid inpart c of Example I, the above product is obtained.

EXAMPLE l7 DL-a-( N-methylamino)-( l ,4-cyclohexadienyl)methylpenicillin By substituting N-methyl-DL-phenylglycine for the D-phenylglycine in part a and otherwise following the,

procedure of Example 1, the above product is obtained.

EXAMPLE 1s DL-a-lN,N-dimethylamino)-( l ,4-cyclohexadienyl)acetic acidFollowing the procedure of Example la, but sub-- stitutingN,N-dimethyl-DL-phenyl glycine for O-phenyl glycine there is obtainedthe above compound.

EXAMPLE l9 DLa-(N,N-dimethylamino)-( 1,4-cyclohexadienyl )methylpenicillin By substitution of DL-a-(N,N-dimethylamino)-(1,4-cyclohexadienyl)acetic acid (1.115 mmole) as the sodium salt for themethyl acetoacetate enamine of D- 2-amino-2-(l,4-cyclohexadienyl)aceticacid, sodium salt in Example 1c, the above compound is obtained.

EXAMPLE 20 D-a-Amino-( l ,4cyclohexadienyl)methyl sodium salt Onemillimole of D-a-amino-(1,4-cyclohexadienyl)methyl penicillin isdissolved in 10 ml. of an 0.01 N aqueous sodium hydroxide solution.Lyophilization of the solution yields the desired sodium salt.

EXAMPLE 21 penicillin,

Disclaimer 3,682,981.-Fmn7e Lee Wez'senbom, Somerset, Joseph EdwardDOZfi/ni, North Brunswick, Geowges Gusta/v Bach, Hightstown, and JackBernstein, New Brunswick, NJ. 2-AMINO-2-(1,4-CYCLOHEXADIENYL) ACETICACID. Patent dated Aug. 8, 1972. Disclaimer filed May 28, 1974, by theassignee, E. R. Squibb cc Sons, Inc. Hereby enters this disclaimer toclaim 1 of said patent.

[Oyfieial Gazette August 27, 1.974.]

2. Acetoacetic ester enamine of N-2-amino-2-(1,4-cyclohexadienyl)aceticacid.
 3. Methyl acetoacetic ester enamine ofN-2-amino-2-(1,4-cyclohexadienyl)acetic acid sodium salt.